The reason why air is a valuable resource is that it breathes the "life gas" every day. This gas covers the surface of the earth layer by layer, is transparent, colorless and tasteless, and is mainly composed of nitrogen and oxygen, which has an important impact on human survival and production. In the natural state, air is colorless and tasteless.

Oxygen in the air is necessary for all aerobic organisms. All animals need to breathe oxygen, so do green plants. In addition, green plants use carbon dioxide in the air for photosynthesis, and air is almost the only source of carbon dioxide needed by all plants. The composition of air is relatively fixed. This is very important for the survival of human beings and other animals and plants. However, with the development of modern industry, harmful gases and smog discharged into the air have changed the composition of the air and caused air pollution. Polluted air will seriously damage human health, affect crop growth, and cause damage to natural resources and buildings.